what should or should not be law? and what should be considered when creating a law?

Normative jurisprudence is essentially political philosophy, and asks "what should law be?", while analytic jurisprudence asks "what is law?". [ John Austin's utilitarian answer was that law is "commands, backed by threat of sanctions, from a sovereign, to whom people have a habit of obedience".[101] Natural lawyers on the other side, such as Jean-Jacques Rousseau, argue that law reflects

essentially moral and unchangeable laws of nature. The concept of "natural law" emerged in ancient Greek philosophy concurrently and in entanglement with the notion of justice, and re-entered the mainstream of Western culture through the writings of Thomas Aquinas.
Hugo Grotius, the founder of a purely rationalistic system of natural law, argued that law arises from both a social impulse—as Aristotle had indicated—and reason.[102] Immanuel Kant believed a moral imperative requires laws "be chosen as though they should hold as universal laws of nature".[103] Jeremy Bentham and his student Austin, following David Hume, believed that this conflated the "is" and what "ought to be" problem. Bentham and Austin argued for law's positivism; that real law is entirely separate from "morality".[104] Kant was also criticised by Friedrich Nietzsche, who rejected the principle of equality, and believed that law emanates from the will to power, and cannot be labelled as "moral" or "immoral".[105][106][107]
In 1934, the Austrian philosopher Hans Kelsen continued the positivist tradition in his book the Pure Theory of Law.[108] Kelsen believed that although law is separate from morality, it is endowed with "normativity"; meaning we ought to obey it. While laws are positive "is" statements (e.g. the fine for reversing on a highway is €500); law tells us what we "should" do. Thus, each legal system can be hypothesised to have a basic norm (Grundnorm) instructing us to obey. ]